1. Field of the Invention
The present invention relates to a novel process for the activation and utilization of fly ash. More particularly, the present invention relates to a process for activating coal fly ash and its subsequent use for the production of electricity and/or in the production of methane, hydrogen and carbon oxides.
2. Description of Art
Fly ash, a waste material produced upon the combustion of powdered coal, has found limited use. U.S. Pat. No. 4,043,831 to Friedman discloses the use of densified fly ash as a heat exchange material for a fluidized bed carbon gasification zone. U.S. Pat. No. 3,328,180 to Bann discloses a type of aggregated coal ash known as "light weight aggregate" useful in concrete mixes and cinder blocks. U.S. Pat. No. 4,252,777 to McDowell et al. discloses a process for the recovery of aluminum and other metals from fly ash.
U.K. patent application GB No. 2 002 726A describes processes for making high BTU gas containing methane and byproduct electricity from low BTU gas containing carbon monoxide and optionally some hydrogen. Generally, the processes are accomplished by contacting the low BTU gas with iron or other Group VIII metals causing disproportionation of the carbon monoxide to carbon dioxide and elemental carbon. The elemental carbon deposits on the Group VIII metal to form a carbonaceous material and carbon monoxide-depleted low BTU gas which is used to generate electricity. The carbonaceous material is contacted with hydrogen to produce a high BTU gas containing methane.
It has been found that fly ash can be activated by the process of the present invention. Once activated, fly ash can disproportionate carbon monoxide to carbon dioxide and elemental carbon. This is especially surprising since unactivated fly ash does not disproportionate carbon monoxide.
Upon disproportionation, elemental carbon deposits on the activated fly ash forming a highly carbonaceous ash. The carbonaceous ash can be burned as a fuel either directly or in combination with other combustible fuels to produce heat and electricity. The carbonaceous ash can alternatively be used for the production of methane, hydrogen and carbon oxides.
The present invention is economically attractive for several reasons. For example, the present invention provides for an inexpensive catalyst source for a number of catalytic processes as well as providing an economical and efficient use for a common waste product. Further, the source of catalytic material is so inexpensive that the catalysts prepared by the processes of the present invention can be employed only for its "active" life and disposed of without regeneration. However, although the catalyst can be disposed of after one or several cycles, it can be recycled simply by utilizing the process of the present invention.